Rectifier.



G. W. PIER/GE. REOTIHER. APPLIQATION FILED FEB.20, 1907.

923,700'. Patented June 1,1909.

War/ggg UNITED c STATES EAT INT OFFICE.

GEORGE W. PIERCE, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO MASSACHUSETTS WIRELESS EQUIPMENT COMPANY, OF BOSTON, MASSACHUSETTS/A CORPORATION OF N EWl YORK.

To all whom it may concern.'

Be it known that I, GEORGE W. PIERCE, citizen of the United Cambridge, Middlesex county, Massachusetts, have invented certain new and useful Improvements in Rectifiers, of which the following is a specification. i

The invention relates to the rectification of alternating currents and is of special importance in connection with the rectification of comparatively large currents such, for instance,- as are employed in charging-storage batteries. Y

In practicing theinventicn, a comparatively small current from the alternating current source is rectified, or rectified anr distorted, and this small current is utilized to control or operate devices which rectify the comparatively large load current.

The rectified, or rectiiied and distorted,

current operates devices to open and close the main, or load, alternating `current circuit, synchronously with theA phase-recurrences thereof. The current for the controlling circuit is derived from the main` alter-- nating source.

The current in the controlling circuit, by which I mean that circuit in which the contrivances for opening and closing the main circuit are `operated, is rectified and distorted so that, instead of a zero point, there is a considerable dormant period, when the currentA is approximately zero, and the current iiow is exclusively in one phase, or much more strongly in one phase than in its opposite. For the purpose of producin this rectified and distorted current, I emp oy in the controlling circuit a contact piece composed of an asymmetrically conductive solid, adapted to rectify small currents, such 'as carborundum, "molybdenite, etc. These asymmetrical conductors are eculiar, in that the current-rise is negligile for kconsiderable rises in potential from the zero point, or phase-axis, Ion both sides of the axis in case of-alternations, and, after. a` considerable rise in potential, the current rises ysuddenly from approximately zero to 'a oint commensurate with the potential. he hase-curve of an alternating current recti ed and distorted by such a substance is characterized bya horizontal (or nearly horizontal) current `line on either side of the Speciicaton of Letters Patent.

States, and resident of,

rent.

Patented June 1, 1909.

Application led February 20, 1907. Serial No. 358,493.

may be more advantageously used than eleotrolytic or other forms of rectiiiers.

The mechanism which is operated or controlled by the rectified, or rectified and distorted, small currentfmay lbe any suitable. form of synchronously operated mechanism operable or controllable by such small cur- For the purpose of illustration I have showrr diagrammatically in the accompanying drawings two forms of apparatus embodying the features of my invention.

In these drawings Figure l is a diagrammatic view Aillustrating one form of apparatus for rectifying a current from an alternating current source; and Fig. 2 is a similar view illustrating a somewhat modified form of apparatus.'

' In the apparatus illustrated in Fig. 1 the conductors o o form the leads from an alternating current source and the electric load which is to be supplied with a rectiiied current from said leads is indicated as a storage batteryc. This load is in circuit with the lead o through a conductor d and is vin circuit with the lead a through conductors e and f and a device for opening and closing the cir- :cuit so that passage of current is permitted in one phase only or more strongly in one phase than in the'opposite phase. The interrupterdevice for opening and closing 'the circuit comprises an armature glconnected with thc "lead a, and arranged to vibrate between two ing device 7L andaconductora. l This recti-A fymg device consists of a crystal or lamina of an asymmetrically conductive substance,

for a considerable period at either side of the y zero point in the alternation. l

Now suppose the rectifying device n offers less resistance to the passage ofthe current in the direction of the arrow than in the opposite direction. The springj and contact 7L are so adjusted that the current in the direction of the arrow is sufiicient to move the armature g into engagement with the ccntact t', thus closing the circuit and permitting the passage of the current in the direction of the arrow through the load c. I/Vhen, however, the electroniotive force of the line diminishes and then reverses, the rectifier n ceases to permit current to pass sucient to hold the armature g so`that during this period of the electromotive force the circuit is open at t. Thus the current is allowed to pass through the contact t' when the electromotive force of the alternating source is in one direction and is not allowed to pass when the electrornotive force is in the opposite di rection. l.

The efficiency of the apparatus may be increased by providing a condenser p of proper capacity' connected in shunt about the mag-` net k for the purpose' of modifying the lag of the current in the inductance at 7C behind the impressed electromotive force. By the use of such a condenser having the proper capacity or so formed that its capacity may be varied to give it the vproper capacity the phase o f the current in the magnet 7c may be so adjusted that the make a'nd breakV of the load V,circuit at the contact t may occur as nearly' as possible at the Vpart 'of the cycle when the voltage of the circuit has the least .tendency to produce sparking at the contact 'L j Any other suitable or wellknown method of using condensers and inductances for regulating the phase of the current in the electromagnet circuit with reference to the phase of the current in the load circuit'may be employed. p j

The movable member operated or controlled electromagnetically through the small rectified current may be formed wholly or partly 4of s/oft'iron or may be\a permanent magnet or an electro-magnet.

The movable member may act with a forced vibration under the action of the s ring j and thefluctuating .current in the e ectromagnet 'le as indicated in Fig. 1 or it may be adjusted or formed to vibrate with some appropriate natural period under its own inertia. -In the latter case Ait may -be constructed as indlcated in Fig. in which cuit, and

the armature is provided with a spring portion g by which it is secured to a support r.

The current may be taken o" from either the contact t or h or both contacts may be used for different rectified circuits as indicated in Fig, 2. As here indicated the contact his in circuit with a second load s through a conductor t and the load is connected with the lead t through a conductor a. In this case two rectified load currents are supplied from the alternating currentl source, the two currents flowing in lopposite directions.

No attempt has been made to illustrate the mechanical details of the apparatus shown which may be such as is best suited to the conditions under which the invention is to be used.

I/Vhat I claim and desire to secure by Letters Patent is 1. In a rectifying apparatus, the combina tion of a main alternating current line, an interrupter therein, a circuit deriving current from the main circuit, an asymmetricallyconductive solid in said derived circuit to rectify and distort the alternating current therein, and devices in said derived circuit to control the interrupter. j 2. In a rectifying apparatus, the combination of a main alternating current circuit, an interrupter therein, a circuit deriving current from the main circuit, an 'asymmetrically conductive solid in said derived circuit to rectify and distort the alternating current therein, and electromagnetic devices in said derived circuit to control the interrupter.

3. In a rectifying apparatus, the combination of a main alternating current circuit, an interrupter therein, acircuit deriving current from the main circuit, an asymmetrically conductive solid in said derived circuit to rectify and 4distort the alternating current cuit, and devices in said derived circuit to control the interrupter.

4. In a rectifying apparatus, the combination of a main alternating current circuit, an

therein, a phase regulator in said derived cirinterrupter therein, a circuit deriving current from the main circuit, an asymmetrically conductive solid in ,said derived circuit to Vrectify .and dlstort the alternating current therein, a phase regulator in said derived cire ectromagnetic devices 1n said derlved clrcuit to control the interrupter.

In witness whereof, I have hereunto set my hand, this y11th day of February 1907.

` GEORGE W. PIERCE.

-In the presence of-- IRA L. FrsH, KATHARINE A. DUGAN. 

